Silicone oil antifoam

ABSTRACT

THE FOAMING OCCAISONED BY THE CONVERSION OF RESIDUAL PETROLEUM STOCKS INTO COKE BY DELAYED COKING PROCESS IS CONTROLLED BY TREATING SUCH STOCKS WITH A POLYDIMETHYL SIOLOXANE WHICH HAS A CENTISTOKE VISCOSITY OF AT LEAST 150,000.

Oct. 24, 1972 J. A. HYDE SILICONE OIL ANTIFOAM 3 Sheets-Sheet 1 Filed March 1, 1971 ANTIFOAM ACTIVITY OF DIFFERENT VISCOSITY SILICONES Silicone dose of .4ppm

60,000 cstk. Silicone x Silicone dilution of ltol [50,000 cstK. SaliconeA l o e od n .80 3

m w h Q 5 A 3 mfitu 2 Z- kt mt SE0.

o TIME IN SECONDS secono 00 SE OF $lLlCONE- Oct. 24, 1972 J. A. HYDE SILICONE OIL ANTIFOAM Filed March 1, 1971 3 Sheets-Sheet 2 ANTI FOAM ACTIVITY OF DIFFERENT VlSCOSITY SILICONES FIG I AS A FUNCTION OFTIME 150.000 csfk. snucone A SlLlCONE DOSE os=.24 PPm 400,000 cs'bK SlLlCONE 0 mucous DILUTIONOF.

l'l'o 250 MWtUrZ ktmzmrt ITO.

TIME IN SECONDS FIRST DOSE OF SILJCONE FIG.11A

o a r .m 0 Em Mn 8 v A n s n I e m I O. I J v w L 1 4 w O l I I I N S 2; A 2 E E I! s an m D O D E //,U,, M m 4 T a a o s A I. 7 6 5 A. 3 7- .wwtus lctmiwt $33k 3 Sheets-Sheet" 5 Filed March 1. 1971 ANTIFOAM ACTIVITY OF DIFFERENT VISCOSITY SILICONES A5 A FUNCTION OF TIME 5 I 0 mm a p m w n o d m w e e n n m 0 MM 0 1. I 5 $3 I I OX U O m w M 4 o O o c c c UH... 9 5 in w. kk k 3 C C C I an O O O r 1 M Q. m A w 1 I I m n o m Qui F. M6225 ZIIQEE v5.6a

TIME IN SECONDS FI RST DOSE OF SILICON o 5 .t onH 7e n VA s m m a q o J A s 1 0 n 4 N o Owm 3 I 4/ r wa 4 WW I \fi J o D J E A? mm I T- /r f 7 ...I 6 5 4 3 2 hmtvg 5 klmlwb Z101 United States Patent Int. Cl. Cg 9/14 US. Cl. 208-131 2 Claims ABSTRACT OF THE DISCLOSURE The foaming occasioned by the conversion of residual petroleum stocks into coke by delayed coking processes is controlled by treating such stocks with a polydimethyl siloxane which has a centistoke viscosity of at least 150,000.

In the processing of various residual petroleum stocks into coke, a commonly used technique is the well-known delayed coking process. In the delayed coking process heavy residual oils are heated to above 500 C. by pumping them at high velocity through a pipe furnace and then changing these oils to an insulated coking drum. This process is further described in the Encyclopedia of Chemical Technology, 2nd edition, volume IV.

The delayed coking process produces quantities of foam which is undesirable since it diminishes the eflicient operation of the process. To control foam in the delayed coking process it is customary to treat the stocks while being processed with polydimethyl siloxane polymers.

The polydimethyl siloxane polymers most commonly used as defoamers in this application are of relatively low molecular weight as evidence by their centistoke viscosities. Typical polydimethyl siloxanes have centistoke viscosities of about 12,500. In a few cases polydimethyl siloxanes have been used which have centistoke viscosities of about 60,000.

The present invention is directed to provide improved defoaming methods for the treatment of petroleum stocks which are subjected to delayed coking processes.

In accordance with the invention it has been found that the foaming of residual petroleum stocks subjected to delayed coking processes may be inhibited by treating said stocks with from 0.05 up to about 100 ppm. of a polydimethyl siloxane which has a centistoke viscosity of at least 150,000. In a preferred embodiment of the invention it is preferred to use polydimethylsiloxanes which have centistoke viscosities ranging between 400,000 to 3,000,000, which are applied in a preferred dosage range of from 0.1 to 10 p.p.m.

To use these viscous polydimethyl siloxanes it is de- 3,700,587 Patented Oct. 24, 1972 ice sirable that they be first dispersed in petroleum hydrocarbon solvents such as kerosenes, naphthas, aromatic oils and the like. In some cases it is desirable to blend oil soluble surfactants with the polydimethyl siloxanes and the petroleum hydrocarbon liquid.

To illustrate the advantages and merits of the invention reference may be had to the drawings, e.g. FIGS. I, II and III, which show the relative merits of the polydimethyl siloxanes used in this invention over other lower molecular weight materials.

The data shown in the FIGS. I, I I and III were based upon the following test procedure:

TEST PROCEDURE l) A test tube is charged with grams of coker feedstock. This sample is heated to 850 F. and maintained at that temperature for the evaluation in order to simulate the conditions of a coking drum.

(2) For the evaluation, different viscosity silicones were diluted with deordorized kerosene. This evaluation was made on a straight weight basis.

(3) The diluted silicone is added one drop at a time.

(4) The foam height is recorded before and immediately after the silicone is added and every 10 seconds thereafter.

(5) When the foam height has reached /2 inch below the initial height, the next drop of antifoam is added. This procedure is continued until 3 drops have been added.

I claim:

1. A method of inhibiting foaming of residual petroleum stocks during their conversion into coke by a delayed coking process which comprises treating said residual petroleum stocks with from 0.05 up to about ppm. of a polydimethyl siloxane which has a centistoke viscosity of at least 150,000.

2. The method of claim 1 where the polydimethyl siloxane has a centistoke viscosity of from 400,000 to 3,000,000 and it is used as a dosage ranging from 0.1 to 10 ppm.

References Cited UNITED STATES PATENTS 2,702,793 2/ 1955 Smith 25278 3,235,502 2/1966 Waldmann 25249.6 3,383,327 5/1968 Sullivan 252358 JAMES E. POER, Primary Examiner A. P. DEMERS, Assistant Examiner US. Cl. X.R. 

